Temperature and relative humidity reported by the radiosonde have long been converted to radio refractive index without regard to sensor time lag. Past studies of radio ducting incidence have shown that under restricted conditions only corrections for humidity sensor lag need be made. It is here shown that lag constants currently in the literature are inadequate under conditions of superrefraction of radio waves. Use of currently available lag constants indicates that, should any correction be made, both temperature and humidity sensor lags must be considered for any climatological comparison of ducting incidence. By ignoring sensor time lag, one tends to underestimate ducting incidence; by correcting only for humidity sensor lag, one tends to overestimate ducting incidence.
Compared to the optimum filters, the suboptimum filters certainly were inferior. Noise was not equally visible in the picture. Small flat areas with surrounding detail seemed to suffer the most, since there the noise visibility was high, and because of the surrounding detail the filter did not average a large number of picture elements and consequently did not efficiently filter out the noise. Compared to the constant (nonadaptive) filter, the performance of the optimum as well as the suboptimum filter was clearly superior. As would be expected, the constant filter either removed the noise or preserved the resolution, but could not do both. One of the causes of degradations in adaptive filters is the adaptation based on the luminance signal. Although the degradations were not visible in most pictures, there were certain places in some pictures where the degradation was visible. If the picture had a few luminance edges which were not accompanied by the chrominance edges, then the noise would not be removed from the chrominance signal. However, in most cases, especially with the optimum filters, the unfiltered noise in the chrominance signal was masked by the edges of the luminance signal and consequently the picture quality did not suffer significantly. If, however, the picture had some chrominance edges which were not accompanied by the luminance edges, the noise was removed and the edges were blurred, resulting in a poor picture. As mentioned earlier, this happened only in some pictures and at very few places in these pictures. It could be corrected to some extent by considering both the chrominance edges and the luminance edges in the definition
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.